1. Field of the Invention
The present invention generally relates to a bicycle chain wheel having a chain drop prevention feature. More specifically, the present invention relates to a bicycle chain wheel with a chain drop prevention feature that prevent the chain dropping off of the large sprocket or gear to the outside of the large sprocket or gear.
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle to make the bicycle easier to assemble and more affordable to purchase and maintain.
One particular portion of a bicycle that has been extensively redesigned over the past years is the drive train of the bicycle. A bicycle drive train typically has a chain that interconnects one or more front gears (chainrings) to one or more sprockets mounted on the rear wheel. The front gears are mounted on the bicycle frame by a bottom bracket that has a crank arm axle that rotates relative to the bicycle frame. Each end of the crank arm axle has a crank arm fixed thereto for rotating the crank arm axle relative to the bicycle frame. The crank arms extend outwardly from the bottom bracket in opposite directions and have pedals attached to their free ends for supporting the rider's feet. The front gears are typically attached to the right crank arm to rotate therewith. Rotation of the pedals by the rider causes the chain wheels to rotate which in turn moves the bicycle chain to rotate the rear sprockets, and thus, rotate the rear wheel of the bicycle.
With a bicycle having a chain wheel such as described above, a front shift control device and a front derailleur, which are typically linked by a shift cable, are used to move the chain between the front gears. In particular, the front derailleur is operated by the shift cable upon actuation of the front shift control device such that the chain is guided or shifted onto the desired front sprocket of the plurality of front sprockets. However, sometimes the chain can drop off from the outer gear and fall between the right crank arm and the outer gear. To avoid the chain from becoming jammed between the right crank arm and the outer gear, the outer gear is sometimes provided with a chain drop prevention pin that extends outwardly from the outer gear towards the right crank arm. While these conventional front chain wheels generally function well with this type of chain drop prevention pin. They do suffer from some deficiencies. In particular, with the above-mentioned conventional front chain wheels, the chain drop prevention pin may be damaged, which would require the entire outer gear to be replaced. Moreover, adding the chain drop prevention pin to the outer gear increases the overall cost of manufacturing the outer chain wheel.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved bicycle chain wheel assembly. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.